m's Q6 pick (2026-05-26): kanban groups the filtered set by `status`
(default) / `area` / `tag` / `management`. Read-only — drag-to-change
is parked. Adds the third view_type render on /tree (alongside list and
card from earlier slices); kanban is now unlocked in PageViewTypes("/").
New web/kanban.go owns BuildKanbanBoard + the per-dimension keyer +
column ordering (status: active/done/archived; management: mai/self/
external/unmanaged; area + tag: alphabetical). Within-column order:
pinned-first → updated_at desc → title.
ParseGroupBy + GroupByChips provide the URL-param hookup and the chip
strip rendered above the board. Multi-tag items appear in every tag
column they belong to (deliberate — the kanban surfaces overlap).
Render:
- handleTree builds the kanban board off the same flatMatchedItems the
card view consumes; cost is one extra grouping pass, no new DB hits.
- New templates/tree_kanban.tmpl: header chip strip + responsive
column board (horizontal scroll on overflow). Empty filtered set
surfaces a friendly nudge.
CSS additions cover the column / card layout; existing chip aesthetics
reused for the group-by toggle.
Test updates:
- view_type_test.go: slice B's "kanban locked on /" assertions tightened
to "kanban unlocked; calendar + timeline still locked on /" — slice C
is the unlock event for kanban.
- New kanban_test.go: per-dimension grouping (status, tag, area),
pinned-first ordering, parser fallback.
- server_test.go: end-to-end render — GET /?view_type=kanban produces
kanban-board markup + group-by chip strip; forest absent.
